Horizon1117ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERESPropagation of subseasonal equatorially-forced coastal trapped waves down to the Benguela upwelling systemScientific Reports - Natureart. 5306 [10 p.]ATLANTIQUEBENGUELA COURANT2019fdi:010075550ENGScientific Reports - Nature2045-2322ISI:00046258560001610.1038/s41598-019-41847-1http://www.documentation.ird.fr/hor/fdi:010075550http://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers19-04/010075550.pdf9Horizon (IRD)The oceanic connection between the coastal variability along the southwestern African coasts and the linear equatorial dynamics at subseasonal time-scales (<120 days) is examined using a variety of model outputs, ranging from linear to general circulation models. We focus on the equatorially-forced fast and weakly dissipative first-mode coastal trapped waves which are shown to propagate down to the southern tip of Africa. In the eastern equatorial Atlantic, the first-mode equatorial forcing is tangled with the higher-order Kelvin wave modes and is overshadowed by the dominant second baroclinic mode. The latter is slower and peaks 10 days after the concealed first-mode contribution. Within this time frame, the remotely-forced first-mode coastal trapped waves impinge on the variability of the Benguela upwelling ecosystem, almost in phase with the subseasonal sea level fluctuations in the Gulf of Guinea. Over 1993-2008, the equatorial forcing undergoes a substantial interannual modulation. Periods of energetic first-mode equatorial Kelvin waves coincide with a strong subseasonal coastal wind activity that breaks the stronger equatorial connection. This suggests the existence of a large-scale atmospheric connection between the equatorial wave forcing and the along-shore winds in the Benguela, modulating the maximum latitude at which the equatorial dynamics impacts the local marine resources.032UR065Afrique du SudAfrique du Sud